Ontwarrende controverse over hersengolven in autismmaart 12, 2020
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Brainwaves are cited as a biological basis for autism, an objective method to diagnose it, and a treatment through EEG-guided neurofeedback. Yet each of these intersections between brainwaves and autism is controversial. These mysterious waves of electromagnetic energy radiating out of the human brain are interrelated with autism, and there is tremendous potential for brainwave science to benefit people with autism, but also much uncertainty.
Brainwaves in autism
Both brainwaves and autism are widely misunderstood by the general public, so confusion in combining the two subjects is inevitable. People associate brainwave recordings (EEG) with epilepsy, but brainwaves are altered in many neurological and even psychological conditions. Transformative research on brainwaves is providing a window into normal brain function, revealing individual differences in cognitive ability, personality, and learning potential.
Autism is thought to involve disruption of coordinated communication between brain regions involved in sensory processing and social behavior. Altered patterns of neural network activity should, in turn, generate differences in brainwave activity in people with autism, and a large body of research supports this prediction. In addition to the possibility of using brainwave analysis to diagnose autism, the alterations in brainwaves provide intriguing clues to the biological basis for the disorder.
Diagnosing autism by brainwaves
In 2013, the FDA approved an EEG marker the theta/beta power ratio, as a diagnostic test for attention-deficit/hyperactivity disorder (ADHD). This was the first EEG method approved by the FDA for diagnosing any psychological condition. This marker is based on a common method of brainwave analysis, which is to break down all the erratic brainwave activity into its component frequencies. The theta/beta ratio is simply the amount of theta brainwave power, which oscillates at 4 to 7 cycles/sec (Hz), recorded at a particular spot on the scalp, divided by the power of the beta brainwaves, which oscillate at a frequency of 13 to 30 Hz. In people with ADHD the theta/beta power ratio is higher than normal in the frontal brain region.
A comprehensive review of studies in the scientific literature, published in 2006, found that the method was 94 percent accurate in diagnosing ADHD. But recent studies suggest that while a large fraction of ADHD patients show this characteristic theta/beta ratio signature, others do not, making the measure an insufficient diagnostic method on its own. Autism and ADHD often coincide. An estimated 30 to 80 percent of children with autism also meet the criteria for ADHD and, conversely, 20 to 50 percent of children with ADHD meet the criteria for autism. Researchers in the Netherlands have proposed that autism and ADHD are, in fact, different manifestations of a single condition with a range of subtypes.
There are several other features of brainwaves that differ in people with autism. More sophisticated analyses determine how well brainwave oscillations in one brain region are synchronized with oscillations in a different region. This is much like two sections of an orchestra playing together in time while other instruments play different parts. That intricately coordinated rhythm among musicians in an orchestra is what makes music, in contrast to the cacophony as they tune-up before a performance. Many believe autism and other mental disorders are the consequence of improper coordination of communication between brain regions. This desynchrony in the autistic brain would disrupt function just as a delay on a telephone call destroys communication.
Treating Autism By Modifying Brainwaves
If optimal brain function is dependent on proper brainwave activity, then methods to alter brainwaves that are disrupted should provide a way to treat mental and neurological dysfunctions. EEG guided neurofeedback is a simple and drug-free way to change brainwave activity. EEG electrodes pick up brainwave activity—say, the theta/beta ratio—and signal the participant with a tone when their brainwave activity shifts toward the “normal” EEG pattern, defined by the average of recordings across a large reference population. In people without autism, recent research shows that neurofeedback can alter alpha waves and improve attention, consistent with many other studies in the literature. Having experienced neurofeedback myself, as I describe in my new book, Electric Brain, I can say that this alteration of brainwave function happens automatically, without conscious effort. Remarkably, the brain will correct itself to the extent possible if given the proper guidance.
A recent assessment of the efficacy of EEG-guided neurofeedback in children by Elizabeth Hurt and colleagues of Wright State University concludes that EEG-based neurofeedback for ADHD is recommended for families who have tried conventional treatments, based on the encouraging outcome of twelve randomized controlled studies in the scientific literature. Neurofeedback training resulted in measurable improvements in sustained attention, sensory/cognitive awareness, communication, and sociability in children with autism.
Yet there is much controversy over the use of neurofeedback as a treatment for autism and many other conditions. Companies, such as Neurocore, which is backed financially by billionaire Betsy DeVos, the U.S. Secretary of Education, and other manufacturers, claim that their neurofeedback devices can treat autism and a host of other conditions, including ADHD, depression, stress, and anxiety. Such claims have been criticized, citing a lack of compelling medical evidence that the method is effective.
An alternative to changing brainwaves through neurofeedback is to modify them directly by using electrical stimulation. Electrical stimulation can be delivered through electrodes implanted in the brain, as is used to treat Parkinson’s disorder. This approach is being used experimentally for treating a wide range of psychological conditions, including autism, not only for treating neurological disease.
Alternatively, electricity can be driven into the brain through the scalp. This can be done easily by mild AC or DC current applied to the head through scalp electrodes or by beaming strong electromagnetic pulses into the brain from powerful electromagnets positioned above the targeted region of the head. In general, these brain stimulation studies are small, exploratory investigations. The effects vary, in part because the most effective stimulation pattern and techniques are not yet clear, but these approaches show promise.
If stimulating the brain with electricity is off-putting, rhythmic lights or sound will profoundly alter brainwaves. Strobe light flickering at the gamma brainwave frequency (40 Hz) or auditory tone stimulation at 40 Hz, activates brain cells called microglia to remove the toxic protein beta-amyloid in a mouse model of Alzheimer’s disease, improving cognitive function.
These studies demonstrate the potential to modify brainwaves easily to benefit people with autism and other cognitive disorders.
Seeing Through the Muddle
It is difficult to distill the findings on brainwaves and autism down to one clear result. The complexity of findings from brainwave research reflects both methodological and biological factors. In part, this is because the methods of brainwave analysis in different studies range from comparing the power of different brainwave frequencies to measuring differences in synchrony in brainwaves across different brain regions. Many studies are relatively small, and therefore the results are less certain, because this area of research is not well funded. The equipment used ranges from simple EEG devices of the type that can be purchased on the internet to advanced brain imaging equipment found only in the most well-equipped research laboratories. The competence of the EEG analysis varies widely, and this factor, as well as the equipment, are crucial in obtaining reliable EEG data. EEG recordings can be fraught with error and inaccuracies caused by eyelid blinks, heartbeat, and other electrical noise created by muscle contractions. The conditions under which the recordings are made are critical, as brainwave activity is so highly responsive to arousal and other cognitive states. The age, gender, and nature of the impairments in test subjects must be carefully considered in designing experiments. Biologically, there is wide variation in brainwave activity among different people in the general population, without any clear cognitive or behavioral impairment. For example, approximately ten percent of the “normal” population do not have alpha waves, but they have no known impairments. Finally, autism is a heterogeneous disorder, which is believed to arise from multiple causes.
The rapid advances in brainwave research are bringing us closer to a better understanding of autism and effective ways to treat it. If brainwaves are coordinating activity among populations of neurons, then deviations from normal EEG activity would be expected in autism, and methods to alter brainwaves would provide a drug-free and relatively safe way to treat the condition.